1. Field of the Invention
This invention relates to a trenchless method and system for installing, repairing, and replacing underground pipelines. In one aspect, this invention relates to a method and system for splitting or bursting pipes. In one aspect, this invention relates to a method and system employing ramming, boring, and drilling for the installation of new pipelines.
2. Description of Related Art
Pipe, such as plastic, copper, lead, steel, cast iron, and the like, has been used for connecting homes and creating networks for utilities such as water, sewage, oil, and natural gas. As the pipes become older, they break down, crack, corrode, develop scaling on interior surfaces that can clog the pipe, etc., thereby requiring repair or replacement. However, the repair and eventual replacement of such pipes is expensive and disruptive of normal activity occurring there above, frequently requiring excavation and trenching along the length of the deteriorated pipe.
Successful alternatives to such trenching and excavation are the trenchless techniques known as “pipe bursting” or “pipe splitting” in which the pipe is broken or split apart in situ using a pipe bursting tool or pipe splitting tool pulled or pushed there through. (It should be noted that, although pipe splitting and pipe bursting are different techniques which produce different results, the terms are frequently used interchangeably in the art.) The pipe bursting tool may also include a spreader which pushes the fragmented pipe remains radially outward into the surrounding soil so that the pipe is effectively, though not actually, removed to make way for replacement pipe. Pipe splitters typically use one or more cutting surfaces to split the pipe material. The cutting surfaces engage against the end of the pipe and are pulled in the direction of the pipe to split the pipe.
Replacement plastic pipe or, alternatively, a larger diameter plastic pipe liner in which the replacement pipe will be received, is usually attached to the back end of the pipe bursting or splitting tool so that it is pulled into place as the old pipe is broken apart or split. Large pulling forces are required to pull cutting surfaces with this configuration through the pipe material and thereby split the pipe. In some cases, where the existing pipe is located in soft soil, the substantial pulling force transmitted from the cutting surfaces to the pipe may actually move the pipe through the soil instead of splitting the pipe material. In some cases, where the pipe is positioned proximate other underground objects, such as water or electric utilities, the substantial pulling force, particularly in the case of pipe bursting, may result in damage to such underground objects due to the displacement of pipe fragments and the surrounding soil resulting from the bursting process.
Referring to FIG. 1, a pipe bursting tool 10 is pulled by a directional drilling machine 11 by means of a drill string 12. The pipe bursting tool is positioned at a starting location, such as a manhole or entrance 13 and pulled through an existing pipeline 14, bursting the pipeline into fragments 15 which remain in the ground. The replacement pipe 16 is drawn along behind the pipe bursting tool, as a result of which the replacement pipe ends up occupying the same space as the existing pipeline.
Other trenchless techniques for installing and/or replacing pipe include ramming in which a hydraulically or pneumatically driven impactor is used to drive the selected tool; boring in which a boring tool is used to bore an opening (borehole) in the ground into which a pipe connected with the back side of the boring tool is pulled into the resulting borehole; and drilling in which a drilling tool is used to drill an opening into which a pipe connected with the back side of the drilling tool is pulled into the resulting opening
Referring to FIG. 2, a pipe 31 to be installed underground is connected with the back side of a drilling or boring tool 30 and is pulled through the borehole 32 created by the drilling or boring tool. Some form of motivation means, such as a rig comprising a rotary table 34 and a thruster 29, is used to push the drilling or boring tool through the ground 42. The rotary table is driven by hydraulic or electric motors and the thruster advances the pipe as the borehole is made in the ground.